Clutch having a pre-clutch and a main clutch

ABSTRACT

A clutch including a pre-clutch and a main clutch, where the pre-clutch can be brought into an engaged or disengaged state by a clamping means, where the pre-clutch is connected via an effective connection to the main clutch, such that in the disengaged position and engaged position are transmitted to the main clutch, where the pre-clutch is arranged between the main clutch and a connection area for an actuating element of the clamping means, that the clamping means is effectively connected to an outer area by means of a clutch hub of the pre-clutch, that the clamping means is effectively connected in a middle area to a disc of the counter-disc of the pre-clutch, and that the clamping means has a contact area for the actuating element in an inner area.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is filed under 35 U.S.C. §120 and §365(c) as acontinuation of International Patent Application No. PCT6E2010/001224filed Oct. 18, 2010, which application claims priority from GermanPatent Application No. 10 2009 051 243.8 filed Oct. 29, 2009, GermanPatent Application No. 10 2009 059 738.7 filed Dec. 21, 2009, and GermanPatent Application No. 10 2010 025 411.8 filed Jun. 29, 2010, whichapplications are incorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The invention relates to a clutch having a pre-clutch and a main clutch.

BACKGROUND OF THE INVENTION

A clutch is known in the prior art from European Patent No. 1685332 B1,having a pre-clutch and a main clutch.

Thus, there is a long-felt need for an improved clutch having apre-clutch and a main clutch.

BRIEF SUMMARY OF THE INVENTION

One object of the invention is that the pre-clutch can be arrangedbetween the main clutch and the actuating element of the pre-clutch.Furthermore, a radial outside area of the clamping means of thepre-clutch is effectively connected to a clutch hub of the pre-clutch,and the radial middle area of the clamping means is effectivelyconnected to a disc or counter-disc of the pre-clutch. In the area lyingradially to the inside, the clamping means has a contact area for theactuating element. This arrangement reduces the inertia of thepre-clutch. The dynamics of the clutch are therefore significantlyimproved.

In one embodiment, a clutch basket of the pre-clutch is rotatablymounted by a bearing to the clutch hub of the pre-clutch. In anotherembodiment, a clutch hub of the main clutch is connected via a torquesensor, especially via spring means, to the clutch hub of thepre-clutch. In yet another embodiment, a clutch hub of the pre-clutch ismounted via a second bearing to a clutch basket of the main clutch. Inyet another embodiment, a second clamping means is provided that clampsthe disc and counter-disc of the pre-clutch against each other.

In another embodiment, a third clamping means is provided thatpretensions the main clutch in the direction of engagement.

In yet another embodiment, means, for example, a tension spring,pressure spring, rubber pressure piece and/or a damper, are providedthat improve the effective connection between the main clutch and thepre-clutch. In particular, these means can dampen vibration or grabbingby the pre-clutch. This feature is independent from the design of theclutch and can be used in various embodiments.

In another embodiment, the first and/or second bearing has means forgenerating basic friction, where the means are preferably designed inthe form of a friction disc and/or in the form of a spring means foradjusting the friction of the bearing. For example, this can dampen thevibration of the pre-clutch. This feature is independent from the designof the clutch and can be used in various embodiments.

In yet another embodiment, the main clutch is effectively connected viaa torque sensor, such as spring means, to the pre-clutch.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The nature and mode of operation of the present invention will now bemore fully described in the following detailed description of theinvention taken with the accompanying drawing figures, in which:

FIG. 1 shows a schematic representation of a first clutch embodiment;

FIG. 2 displays representations of slopes of ramp surfaces of a rampdevice;

FIG. 3 shows a perspective partial cross-sectional view of the clutchillustrated in FIG. 1;

FIG. 4 shows a cross-sectional view through the middle of the clutchfrom FIG. 3;

FIG. 5 shows a schematic representation of a second clutch embodiment;

FIG. 6 shows a schematic representation of a third clutch embodiment;

FIG. 7 shows a schematic representation of a fourth clutch embodiment;

FIG. 8 shows a schematic representation of a fifth clutch embodiment;

FIG. 9 shows a schematic representation of a sixth clutch embodiment;

FIG. 10 shows a schematic representation of a seventh clutch embodiment;and,

FIG. 11 shows a schematic representation of an eighth clutch embodiment.

DETAILED DESCRIPTION OF THE INVENTION

At the outset, it should be appreciated that like drawing numbers ondifferent drawing views identify identical, or functionally similar,structural elements of the invention.

While the present invention is described with respect to what ispresently considered to be the preferred aspects, it is to be understoodthat the invention as claimed is not limited to the disclosed aspects.

Furthermore, it is understood that this invention is not limited to theparticular methodology, materials and modifications described and, assuch, may, of course, vary. It is also understood that the terminologyused herein is for the purpose of describing particular aspects only,and is not intended to limit the scope of the present invention, whichis limited only by the appended claims.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which this invention belongs. Although any methods, devicesor materials similar or equivalent to those described herein can be usedin the practice or testing of the invention, the preferred methods,devices, and materials are now described.

FIG. 1 shows a schematic representation of a partial section of one halfof clutch 1. arranged around rotational axis 2 having pre-clutch 3 andmain clutch 4. Clutch 1 is a wet clutch. Pre-clutch 3 and the mainclutch are effectively connected to each other by means of effectiveconnection means 12. In first clutch basket 5 of pre-clutch 3, firstdisc 6 is suspended non-rotatably and slightly shiftable axially alongrotational axis 2, and, for example, includes drivers or friction discscoated with friction material. Only first disc 6 is shown in theportrayed embodiment. Plurality of first discs 6 can also be provided.In addition, each first disc 6 is assigned first counter-disc 7, wherefirst counter-discs 7 are accommodated non-rotatably and axially movablealong rotational axis 2 in first clutch hub 8 of pre-clutch 3. In oneembodiment, first clutch hub 8 is connected to transmission input shaft15. First disc 6 is a driver disc, and the first counter-disc is a disc.First counter-discs 7 are, for example, made of steel.

First clutch hub 8 has outer and inner plates 81, 82, between whichfirst disc 6 and first counter-disc 7 are arranged. Furthermore,clamping means 10, for example, in the form of a disc spring thatcompresses first disc 6 and first counter-disc 7, and therefore,connects first clutch basket 5 to first clutch hub 8 non-rotatably,thereby engaging clutch 3. First clutch basket 5 is rotatably mounted bymeans of bearing 13 to first clutch hub 8. When pre-clutch 3 isdisengaged, first clutch basket 5 can rotate in relation to first clutchhub 8.

Clamping means 10 rests against inner plate 82 in radially outside area101. In radially middle area 103, first clamping means 10 lies againstthe bottom side of first counter-disc 7. In a radially inner area,clamping means 10 has another contact area 102 for an effectiveconnection to an actuating element.

First clutch basket 5 has first ramp ring 11 that is assigned to secondramp ring 21 of main clutch 4. First ramp ring 11 is, for example, partof a connecting piece of first clutch basket 5 that is guided to bearing13. Transmission element 22 is formed between first ramp ring 11 andsecond ramp ring 21, for example, in the shape of a ball. First rampring 11, transmission element 22, and second ramp ring 21 representeffective connection means 12 between pre-clutch 3 and main clutch 4.

Second ramp ring 21 can be designed as part of a cover of main clutch 4.Second ramp ring 21 is fastened non-rotatably and slightly axiallyshiftable along rotational axis 2 in second clutch basket 16 of mainclutch 4. Main clutch 4 has two discs 17 that are suspendednon-rotatably and slightly axially shiftable along rotational axis 2 insecond clutch basket 16. In addition, main clutch 4 has second clutchhub 18 in which two counter-discs 19 are suspended non-rotatably andslightly axially shiftable along rotational axis 2. Second discs 17 andsecond counter-discs 19 are arranged in alternate layers as shown inFIG. 1. Second clutch hub 18 is connected via torque sensor 23 to firstclutch hub 8. Torque sensor 23 is designed in the form of a helicalspring and represents an elastic connection between first clutch hub 8and second clutch hub 18. Second discs 17 are, for example, made ofdriver or friction discs coated with friction material. Secondcounter-discs 19 are, for example, made of steel. Second discs 17 andsecond counter-discs 19 are arranged between second ramp ring 21 andsecond plate 20. In one embodiment, second plate 20 is a part of secondclutch basket 18 and is guided to engine input connection 24.

First effective connecting means 12 is a ramp device in the form offirst ramp ring 11 and second ramp ring 21, where first ramp ring 11 andsecond ramp ring 21 have sloped surfaces on facing sides. Transmissionelement 22 is arranged between the sloped surfaces. The basic functionof the ramp device is to shift second ramp ring 21 a greater or lesserdistance toward second plate 20, depending on the windup angle betweenfirst ramp ring 11 and second ramp ring 21. The path of movement isdesigned such that main clutch 4 is engaged or disengaged, depending onthe windup angle.

In one embodiment, transmission element 22 can also be designed in theform of cylindrical rollers. For example, three or more balls orcylindrical rollers can be provided to convert the twist of first rampring 11 in relation to second ramp ring 21 into an axial movement ofsecond ramp ring 21 toward second plate 20 and thereby engage mainclutch 4.

If clamping means 10 is not actuated, a friction lock forms betweenfirst disc 6 and second counter-disc 7 and thereby engages pre-clutch 3.If torsion results between first ramp ring 11 and second ramp ring 21due to differences in torque between transmission input shaft 15 andengine output 24 when pre-clutch 3 is engaged, main clutch 4 isautomatically engaged in a friction lock. After the internal combustionengine starts, second clutch basket 16 and second ramp ring 21 rotate inrelation to first ramp ring 11 in response to torque on transmissioninput shaft 15, for example, from an engaged gear, or slip torque whenpre-clutch 3 is engaged. Transmission element 22 is shifted onto arising ramp in the direction of tension, where axially fixed first rampring 11 axially shifts the axially shiftable ramp ring 21 toward secondplate 20. By means of the axial movement of second ramp ring 21, layeredsecond discs 17 and second counter-discs 19 are clamped together andengaged in a friction lock. This friction locks main clutch 4.

To disengage clutch 1, pre-clutch 3 merely has to be disengaged byactuating clamping means 10 toward main clutch 4. Pre-clutch 3 isdesigned such that pre-clutch 3 is engaged when clamping means 10 is notactuated. Pre-clutch 3 is a so-called active clutch, where clampingmeans 10 lies against first clutch hub 8. This significantly reduces theinertia of pre-clutch 3. The dynamics of clutch 1 are thereforesignificantly improved. In one embodiment, torque sensor 23 can also bediscarded. Torque sensor 23 ensures that the load change is dampenedbetween engine connection 24 and transmission input shaft 15.

FIGS. 2 a, 2 b and 2 c show a schematic representation of threepositions of effective connection means 12, which clarifies theoperation of the ramp rings. FIGS. 2 a, 2 b and 2 c each show a sectionof first ramp ring 11, second ramp ring 21, and transmission element 22,in the form of a ball. The cross-sections run along a radialcircumference in reference to a circle midpoint of first ramp ring 11and second ramp ring 21. First ramp ring 11 and second ramp ring 21 eachhave a ramp surface 60, 61, respectively. FIG. 2 a shows an initialposition in which pre-clutch 3 is disengaged, and no force istransmitted from pre-clutch 3 to main clutch 4. FIG. 2 b shows a tensionposition in which pre-clutch 3 is engaged, and second ramp ring 21 istwisted in relation to first ramp ring 11 due to the accumulated torque.Since first ramp ring 11 is clamped in an axial direction, force isexerted on second ramp ring 21 due to angled ramp surfaces 60, 61, andsecond ramp ring 21 is moved downward toward second plate 20. Thisengages main clutch 4.

FIG. 2 c depicts a state of thrust in which first ramp ring 11 advancesahead of second ramp ring 21, and second ramp ring 21 is presseddownward toward second plate 20 which reengages main clutch 4. Dependingon the angles of the ramp surfaces, predetermined shifting functions canbe set between pre-clutch 3 and main clutch 4.

FIGS. 2 d, 2 e and 2 f show three diagrams of three different rampsurfaces in which path of travel S of the second ramp ring is plottedagainst displacement angle W between first ramp ring 11 and second rampring 21. The diagrams plot the resulting displacement path along whichsecond ramp ring 21 is pushed towards second plate 20. One or two rampsurfaces can be used to realize the displacement path. In “Version a”shown in FIG. 2 d, the rise of displacement path S is much steeper underthrust than under traction. The rise of the resulting displacement pathremains constant on both sides of the home position. In “Version b”shown in FIG. 2 e, the displacement path rises strongly in first sectionA starting from home position in the direction of traction, thentransitions into a lesser slope in second section B. In “Version c”shown in FIG. 2 f, the transition from the steeper section to the secondflatter section is rounded on the pull side. The operation of the clutchcan be improved by the different slopes of the thrust or tractiondisplacement paths.

The design of the ramp surfaces can be harmonized with the two basicoperating states of the clutch.

One state exists when the engine supplies positive torque, for example,when the driver presses the accelerator and thereby subjects clutch 1 totraction. When the engine supplies negative torque, for example, whenbraking the engine, the clutch is subject to thrust. As a function oftraction mode or thrust mode, the pre-clutch accordingly twists in oneor the other direction proceeding from home position relative to themain clutch. Ideally, maximum engine torque should be transmissible intraction mode. In contrast, reduced, limited engine torque is requiredin thrust mode. For example, when the clutch is used in a motorcycle,the rear wheel of the motorcycle can seize more easily in thrust mode.Whereas the rear wheel bears most of the weight of the motorcycle duringacceleration (under a traction load), the front wheel assumes the weightof the motorcycle during braking while braking the engine and henceunder a thrust load. This means that the skid limit of the rear wheel isreached faster in thrust load than in traction mode. For example, whendownshifting from a gear with a higher transmission ratio to a gear witha lower transmission ratio, the engine briefly supplies high negativetorque, which could cause the rear wheel to seize. Due to thissituation, a lower slope of the effective ramp surface or ramp surfacesin traction mode is advantageous so that maximum torque can betransmitted to the engine. The skidding of the rear wheel whiledownshifting can, for example, be avoided when less transmissible torquearises in thrust mode. The pressure should be reduced, which can begenerated by a steep slope.

The shape of the ramp surfaces, i.e., the slope of displacement path Sproceeding from home position as a function of the windup angle alsoinfluences the dynamic sensitivity of the clutch in that the slope ofthe displacement path can shift the natural frequency of the pre-clutch.The steeper the slope of the displacement path, i.e., the steeper theincline of the ramp surfaces, the higher the natural frequency. This hasa positive influence on the dynamics, but has a negative influence onthe transmission of torque. It is therefore preferable to design theshape of the ramp surfaces such that the incline of the displacementpath is in two steps as the windup angle increases as shown in FIG. 2.The effective traction ramp may not be steeper in the ventilationpassage area since the main clutch is not yet engaged and nottransmitting any torque.

Consequently, a rounded transition between two sections A, B can beselected as shown in FIG. 2 f. The advantage of the rounded transitionbetween two sections A, B with different slopes is that the transmissionmeans does not have to be lifted from the ramp surface.

FIG. 3 shows a perspective view of a partial cross-sectional view ofclutch 1. The pre-clutch is arranged in the top area that is effectivelyconnected via effective connection means 12 to main clutch 4 arranged inthe bottom area. Outer plate 81 is screwed tightly to inner plate 82.First disc 6 lies against the inside of outer plate 81 that is fixed bymeans of tabs 25 in a recess of first clutch basket 5 against rotatingin relation to clutch basket 5, although an axial shift along rotationalaxis 2 is possible. First counter-disc 7 is arranged under first disc 6,which is suspended non-rotatably in first clutch hub 8. Firstcounter-disc 7 is also mounted in first clutch hub 8 so as to beshiftable in an axial direction parallel to rotational axis 2. Clampingmeans 10 is arranged in the form of a disk spring on a bottom side ofcounter-disc 7. Both first disc 6 and first counter-disc 7 as well asclamping means 10 can have the basic shape of a circular disc. Likewise,inner plate 82 has the basic shape of a circular disk, and inner plate82 has annular bead 26 on a top side of the radial outside edge areathat extends toward outer plate 81. Radial outer first edge area 27 ofclamping means 10 lies on bead 26. Furthermore, a bottom side of firstcounter-disc 7 facing clamping means 10 has second annular peripheralbead 28 in a radial middle area. In one position, clamping means 10exerts force on first counter-disc 7 by contacting second bead 28 suchthat first counter-disc 7 presses first disc 6 against outer plate 81 toestablish a friction lock between first disc 6 and first counter-disc 7to engage pre-clutch 3. In a radially inner area, clamping means 10 hascontact surface 29 for actuating means 30. Actuating means 30 isdesigned in the form of an annular sleeve and is connected to anactuating element (not shown in FIG. 3) in the form of a clutchcontroller. To disengage clutch 1, actuating means 30 is pressed by theactuating element downward toward main clutch 4. This moves disc spring10 toward inner plate 82 to release the initial tension on firstcounter-disc 7. This disengages the friction lock between first disc 6and first counter-disc 7.

Inner plate 82 is connected to first clutch hub 8. First clutch hub 8has hub 31 for connecting a transmission input shaft. First clutchbasket 5 is connected to first ramp ring 11, and first ramp ring 11 isarranged below inner plate 82. Second ramp ring 21 is assigned to firstramp ring 11 and is arranged partially below first ramp ring 11. Secondramp ring 21 is pre-tensioned in the direction of first ramp ring 11 bya pre-tensioning spring 32 that abuts second clutch basket 16. Pluralityof bias springs 32 is provided, whereas only one is shown. Second rampring 21 is simultaneously a cover for main clutch 4. Second ramp ring 21can be shifted in an axial direction along rotational axis 2 by secondtabs 33 in the recesses of second clutch basket 16; however, they areconnected non-rotatably in a radial direction to second clutch basket16. Furthermore, four second discs 17 are held non-rotatably but axiallyshiftable along rotational axis 2 in second clutch basket 16. Secondclutch basket 16 is connected to second plate 20, where second plate 20is connectable to the engine shaft. Main clutch 4 also has secondcounter-discs 19 that are held non-rotatably to second clutch hub 18although shiftable in the axial direction of rotational axis 2. Secondclutch hub 18 is coupled via plurality of torque sensors 23 designed inthe form of helical springs to first clutch hub 8. Sensors 23 ensurethat an elastic connection exists between first clutch hub 8 and secondclutch hub 18 via helical springs 11.

First ramp ring 11 is rotatably supported about rotational axis 2 onfirst coupling hub 8 via bearing 13. Bearing 13 has outer bearing shell34, inner bearing shell 35, and bearing rollers 36 arranged betweenthem. Outer bearing shell 34 lies against first ramp ring 11. Innerbearing shell 35 lies against first clutch hub 8. Outer bearing shell 34and inner bearing shell 35 roll on each other across bearing rollers 36.

FIG. 4 shows another cross-sectional view of clutch 1 through rotationalaxis 2 and the middle of clutch 1.

FIG. 5 shows a schematic representation of another embodiment of clutch1 that has substantially the same design as in FIGS. 1 through 3. Incontrast to the embodiment in FIGS. 1 through 3, bearing 13 is arrangedbetween first clutch basket 3 and second clutch basket 16 in thisembodiment. In another embodiment, the bearing can also have means forthe basic friction as shown in FIGS. 3 and 4.

FIG. 6 shows another embodiment similar to FIG. 1 where a pre-tensioningspring 40 is also provided, and outer plate 81 is movably pre-tensionedin an axial direction with the assistance of pre-tensioning spring 40parallel to rotational axis 2 against stop 41 of first clutch hub 8 inthe direction of first disc 6. Lining resilience is thereby provided inpre-clutch 3. This improves the initial operation of clutch 1.

In addition, second pre-tensioning spring 42 is provided that is clampedbetween second plate 20 and bottom second disc 43. Lining resilience isthereby provided in main clutch 4. In another embodiment, additionalspring means 44 and/or damping means 45 can be provided to give secondramp ring 21 a defined torsion and/or pressure or damping. In oneembodiment, spring means 44 and damping means 45 are arranged betweensecond stop 46 of second clutch basket 16 and second ramp ring 21. Thedamping means can, for example, be designed in the form of a rubberelement or a damping plunger.

In another embodiment, shown in FIG. 7 and similar to that shown in FIG.6, damping means 45 are arranged between second ramp ring 21 and secondstop 46.

Furthermore, second spring means 47 are clamped between first ramp ring11 and second ramp ring 21. Second spring means 47 is, for example,designed in the form of a tension spring. In one embodiment, springmeans 47 could also be designed in the form of a compression spring.Pre-tension is thereby enabled between first ramp ring 11 and secondramp ring 21.

FIG. 8 shows another embodiment of clutch 1 similar to that shown inFIG. 1, although torque sensor 23 is arranged between first clutchbasket 5 and second clutch basket 16. In addition, first clutch basket 5is connected to engine connection 24. In addition, second clutch hub 18is connected to transmission input shaft 15. Second plate 20 isconnected to second clutch hub 18. First clutch hub 8 rotatably abutssecond clutch hub 18 via bearing 13. Second ramp ring 21 is fastened tosecond clutch hub 18. First ramp ring 11 is fastened to first clutch hub8. Clamping means 10 abuts first ramp ring 11. In one embodiment, firstclutch basket 5 can also be coupled to a transmission input shaft, andsecond clutch hub 18 can be coupled to an engine shaft. Bearing 13 canbe designed with or without means to variably set the basic friction.

FIG. 9 shows the embodiment depicted in FIG. 5 with a schematicrepresentation of bearing 13 having means for the basic friction. Thebasic friction in bearing 13 can, for example, be achieved with frictiondisc 65 that is inserted between bearing shells 34, 35 and contactsurfaces 37, 38. In addition, clamping means 39 is provided which isclamped between contact surfaces 37, 38 formed on first clutch basket 5and second clutch basket 16 and bearing shells 34, 35. The goal of thebasic friction is to brake the relative rotational movement betweenouter bearing shell 34 and inner bearing shell 35 of bearing 13. Thiscan dampen the rotational vibration of pre-clutch 3 in relation to theengine. This is achieved by pre-tensioning the bearing shells with theassistance of clamping means 39. The pre-tensioning from clamping means39 also affects both sides of the friction disc such that frictionaltorque is generated between pre-clutch 3 and engine, where both theouter bearing shell and the inner bearing shell rub against the frictiondisc. This brakes the torsion between the pre-clutch and main clutch.When main clutch 4 transmits torque, pressure arises on bearing 13,which modulates the frictional torque in bearing 13. The pressure alsoacts on the pre-clutch and clamps clamping means 39. This additionalforce attenuates the pre-tension on inner bearing shell 35 so that thefrictional torque on inner bearing shell 35 is at least reduced orcompletely eliminated. The basic friction system of bearing 13 canaccordingly be influenced by the pressure of the main clutch. As long asthe pressure from main clutch 4 is greater than the pressure fromclamping means 39, the basic friction is inactive. In contrast, when thepressure from the main bearing is low, such as while engaging, thebearing rotation is braked.

During a synchronization phase of clutch 1, that is, when thetransmission is progressively being connected to the engine, pre-clutch3 can be excited to vibrate, which then causes the clutch to grab.During this phase, the pressure of main clutch 4 continuously increases.Since the basic friction system of bearing 13 depends on the pressurefrom main clutch 4, the pre-clutch is increasingly braked as thepressure decreases. This can reduce the grabbing of the clutch.

FIG. 10 shows another embodiment similar to that shown in FIG. 8, wherethe pre-clutch is designed as an active clutch. In this embodiment,clamping means 10 is arranged such that the clamping means abuts firstclutch basket 5. In this embodiment, first clutch hub 8 is connected toan engine output. Second clutch hub 18 is connected to an input of atransmission. In this embodiment, pre-clutch 3 is only connected to theengine when the pre-clutch is engaged. When the clutch pedal is pressed,the acceleration of the engine does not affect in the pre-clutch. Firstramp ring 11 is not activated.

FIG. 11 shows another embodiment of the clutch similar to that shown inFIG. 10, where bearing 13 has friction disc 65 and clamping means 39that can set the basic friction according to the function as describedin FIG. 9. This can reduce the vibration resonance of pre-clutch 3.Clamping means 39 and the friction disc are thereby effectivelyconnected to the outer bearing shell 34 and/or inner bearing shell 35,such that the basic friction on bearing 13 depends on the pressure frommain clutch 4. Once the pressure from main clutch 4 is less than thepressure from clamping means 39, basic friction arises, and the rotationof bearing 13 is braked. Once the pressure from main clutch 4 is greaterthan the pressure from clamping means 39, the basic friction isinactive.

Thus, it is seen that the objects of the present invention areefficiently obtained, although modifications and changes to theinvention should be readily apparent to those having ordinary skill inthe art, which modifications are intended to be within the spirit andscope of the invention as claimed. It also is understood that theforegoing description is illustrative of the present invention andshould not be considered as limiting. Therefore, other embodiments ofthe present invention are possible without departing from the spirit andscope of the present invention.

LIST OF REFERENCE CHARACTERS

-   1 Clutch-   2 Rotational axis-   3 Pre-clutch-   4 Main clutch-   5 First clutch basket-   6 Disc-   7 Counter-disc-   8 First clutch hub-   10 Clamping means-   11 First ramp ring-   12 Effective connection means-   13 Bearing-   15 Transmission input shaft-   16 Second clutch basket-   17 Second discs-   18 Second clutch hub-   19 Second counter-discs-   20 Second plate-   21 Second ramp ring-   22 Transmission element-   23 Torque sensor-   24 Engine connection-   25 Tab-   26 Bead-   27 First edge area-   28 Second bead-   29 Contact surface-   30 Actuating means-   31 Hub-   32 Pre-tensioning spring-   33 Second tab-   34 Outer bearing shell-   35 Inner bearing shell-   36 Bearing roller-   37 First contact surface-   38 Second contact surface-   39 Clamping means-   40 Pre-tensioning spring-   41 Stop-   42 Second pre-tensioning spring-   43 Bottom second disc-   44 Spring means-   45 Damping means-   46 Second stop-   60 Ramp surface-   61 Ramp surface-   65 Friction means-   81 Outer plate-   82 Inner plate-   102 Additional contact area-   101 Outer area-   103 Middle area

1. A clutch comprising: a pre-clutch; and, a main clutch, wherein thepre-clutch can be brought into an engaged or disengaged state by aclamping means, wherein the pre-clutch is connected via an effectiveconnection to the main clutch, such that in the disengaged position andengaged position are transmitted to the main clutch, wherein thepre-clutch is arranged between the main clutch and a connection area foran actuating element of the clamping means, that the clamping means iseffectively connected to an outer area by means of a clutch hub of thepre-clutch, that the clamping means is effectively connected in a middlearea to a disc of the counter-disc of the pre-clutch, and that theclamping means has a contact area for the actuating element in an innerarea.
 2. The clutch as recited in claim 1, wherein a clutch basket ofthe pre-clutch is rotatably mounted to the clutch hub of the pre-clutchby means of a bearing.
 3. The clutch as recited in claim 1, wherein themain clutch is effectively connected via a torque sensor to thepre-clutch.
 4. The clutch as recited in claim 1, wherein the main clutchis effectively connected via a torque sensor, including a spring means,to the pre-clutch.
 5. The clutch as recited in claim 1, wherein a clutchbasket of the pre-clutch is rotatably mounted to a clutch hub of themain clutch by means of a bearing.
 6. The clutch as recited in claim 1,wherein the pre-clutch has a disc that is suspended in a clutch basketof the pre-clutch, wherein the pre-clutch has a counter-disc that issuspended in a clutch hub of the pre-clutch, and wherein apre-tensioning spring is provided that pre-tensions the disc and thecounter-disc in the direction of the clamping means.
 7. The clutch asrecited in claim 1, wherein the main clutch has a disc and acounter-disc that can be friction-locked to a cover, and that a secondpre-tensioning spring is provided that pre-tensions the disc and thecounter-disc in the direction of the cover.
 8. The clutch as recited inclaim 1, wherein the effective connection between the pre-clutch and themain clutch is provided in the form of a ramp ring of the pre-clutchthat is effectively connected via a transmission element to a ramp ringof the main clutch, such that a twist of the main clutch in relation tothe pre-clutch disc is converted into an axial shift of the ramp ring ofthe main clutch, wherein means are provided, which improve the effectiveconnection between the ramp ring of the main clutch and the ramp ring ofthe pre-clutch, wherein a tension spring, compression spring, rubberpressure piece or a damper are provided.
 9. The clutch as recited inclaim 2, wherein the bearing is arranged between a ramp ring of thepre-clutch and a ramp ring of the main clutch, and that the bearing hasmeans for generating basic friction, including a friction disc, andspring means for setting the friction.
 10. The clutch as recited inclaim 9, wherein the bearing is designed as a roller bearing, comprisingan outer bearing shell, a plurality of bearing pins and an inner bearingshell, wherein the means are effectively connected to the outer andinner bearing shell.
 11. The clutch as recited in claim 9, wherein thebearing is designed as a roller bearing, comprising an outer bearingshell, a plurality of bearing pins and an inner bearing shell, whereinthe means are effectively connected to the outer or inner bearing shell.12. The clutch as recited in claim 8, wherein the ramp ring of thepre-clutch and the ramp ring of the main clutch have ramp surfaces thatare designed such that differently angled ramp surfaces are active forthrusting and traction, wherein sections act with different slopes. 13.The clutch as recited in claim 8, wherein the ramp ring of thepre-clutch or the ramp ring of the main clutch have ramp surfaces thatare designed such that differently angled ramp surfaces are active forthrusting and traction, wherein sections act with different slopes. 14.The clutch as recited in claim 13, wherein the transition between thesections of the different slopes of the ramp surfaces is rounded. 15.The clutch as recited in claim 8, wherein a second spring element isarranged between the ramp ring of the main clutch and the ramp ring ofthe pre-clutch.
 16. The clutch as recited in claim 8, wherein a springmeans and a damping means is arranged between the ramp ring of the mainclutch and a clutch basket of the main clutch.
 17. The clutch as recitedin claim 8, wherein a spring means or a damping means is arrangedbetween the ramp ring of the main clutch and a clutch basket of the mainclutch.
 18. The clutch as recited in claim 9, wherein the means forgenerating the basic friction in the bearing is designed such that thebasic friction decreases as the torsion between the pre-clutch and mainclutch increases.
 19. The clutch as recited in claim 1, having abearing, wherein the bearing has a means for adjustable friction betweenthe main clutch and the pre-clutch.